Daily, package delivery companies collect millions of packages from thousands of locations scattered over large geographical areas and transport them to sorting facilities for processing. After processing, the packages are carried to an equally large number of destinations. To meet the rigorous schedule of today's business environment while providing accurate deliveries of packages, sorting facilities are equipped with automated transfer systems whenever possible. These transfer systems must be fast, durable, easy to repair or replace, and provide gentle but accurate handling of each package. Furthermore, automatic sorting systems are often used in connection with handling product inventories, assembling ordered items for shipment, and delivering parts to locations where they are needed in manufacturing operations.
Parcel shipping companies now have sorting facilities equipped with automated sorting and transfer systems that provide significantly improved package handling compared to manual labor. Some of these known sorting systems tilt tray conveyor systems in which packages to be sorted are loaded on tilt trays. The trays are mounted on carriages that are driven in lines or trains past one or more loading stations at which packages are placed on the trays. The trays are then moved past a plurality of unloading stations each corresponding to a geographical destination. Typically, each package is loaded alone onto the first empty tilt tray as it passes the loading station and is unloaded at an unloading station corresponding with the package's geographic destination. Examples of tilt tray sorting systems are shown and described in U.S. Pat. Nos. 5,570,773 and 5,388,681. Other systems remove packages from trays or conveyors by pushing them off laterally or diverting them with stationary or pivoting barriers. Others use live roller beds to discharge the packages. All of these systems typically discharge one package at a time. Further examples of sorting systems may be found in U.S. Pat. Nos. 5,655,643; 5,868,239; 5,284,252; 5,441,141; PCT Publication No. WO98/08759; PCT Publication No. WO98/31614; PCT Publication No. WO98/31615; PCT Publication No. WO98/33729; and PCT Publication No. WO98/49076.
The capacity of an automated sorting system depends on the number of trays, the number of loading and unloading stations, and the speed of the equipment. During holiday seasons when package volume is high, the capacity of the sorting system can become a limiting factor in the delivery company's ability to make promised delivery deadlines. However, it may not be practical to increase the number of trays, the number of loading and unloading stations, or the speed of the system. For example, the size of the sorting facility may be limited by the available space.
The tilt trays of these known sorting systems are sized for receiving the largest of a variety of differently sized packages. Only in rare circumstances does a single package require the entire surface of a single tray. Thus, the carrying capacity of the tilt trays generally is under-utilized.
Accordingly, in order to increase the throughput rate of automated sorting systems, there is a need for a loading system for placing a plurality of objects bound for the same geographic destination on a single tray.